When travelling on roads, a wheeled crane needs to meet the requirements of bridge load limit. In accordance with the JB/T 6042-2006 Special Chassis for Truck Crane, the bridge loads of vehicles on roads should be less than or equal to 12 t; and based on the GB1589-2004 Limitations to Outline Dimensions, Shaft Loads and Masses of Road Vehicles, the total masses of the vehicles on roads should be less than or equal to 55 t. At present, the total weights of most large-tonnage wheeled cranes are large, and the bridge loads and the total weights all exceed the standard requirements. Therefore, before travelling on the roads, a part of or all of the supporting legs of these crane products need to be demounted, and the supporting legs are mounted prior to operation.
Specifically, when the wheeled crane is in operation, the crane and its accessories need to be transported to a work site in advance; after arriving at the work site, the components are assembled, and a lifting operation is carried out after the components are assembled. In general, small-tonnage wheeled cranes can arrive at operation sites in complete states, and the accessories or the like do not need to be transported by other auxiliary vehicles. However, the large-tonnage wheeled cranes have large total weights and numerous accessories, and thus the accessories need to be transported by the auxiliary vehicles. Referring to FIG. 1, FIG. 1 is a schematic diagram of a lifting operation state of a wheeled crane in the prior art. The wheeled crane includes a chassis 13, supporting legs 11, and an operation part 12, and the operation part 12 is used for lifting a weight 14.
Wheeled crane: a crane driven by wheels for travelling.
Main crane: a crane used for completing a main body lifting task.
Auxiliary crane: a crane assisting the main crane in completing the lifting operation, or a crane used for assembling the main crane.
Operation part: a part used for lifting weights on the crane, which mainly refers to a mechanism above the chassis of the crane.
Chassis: a part on the crane which is used for travelling and supporting the operation part of the crane, and meanwhile can provide support during a boarding operation of the operation part.
Supporting leg: a supporting mechanism during the operation of the wheeled crane and functioning to support the crane and the weights. Movable supporting legs need to stretch out or swing out to expand supporting spans during the operations of the crane, and meanwhile include vertical supporting mechanisms. According to whether the supporting legs need to extend and retract (or swing) prior to and after the operations, the supporting legs are divided into movable supporting legs and fixed supporting legs. According to different telescopic manners, the movable supporting legs include swing supporting legs and telescopic supporting legs.
At present, during the operations of the wheeled crane, supporting operations of the supporting legs are needed in general, and the supporting legs on the wheeled crane can be arranged in one of the following manners: an H-shaped supporting leg (referring to FIG. 2a), a K-shaped supporting leg (referring to FIG. 2b) and an X-shaped supporting leg (referring to FIG. 2c). The number of the supporting legs is mostly 4, and a fifth supporting leg is also added below the cabs of some products to facilitate front operations of the vehicles.
Referring to FIG. 2a, the H-shaped supporting leg contains four telescopic supporting legs 16 and four fixed supporting legs 17 in the front and back in total, the telescopic supporting legs 16 are arranged on the fixed supporting legs 17, and the fixed supporting legs 17 are connected with the vehicle frame. Referring to FIG. 2b, the K-shaped supporting leg contains two swing supporting legs 15 in the front, and two telescopic supporting legs 16 and two fixed supporting legs 17 in the back in total, wherein the telescopic supporting legs 16 are arranged on the fixed supporting legs 17, and the fixed supporting legs 17 are connected with the vehicle frame. Referring to FIG. 2c, the X-shaped supporting leg contains four swing supporting legs 15 in the front and back in total.
The telescopic supporting legs 16 and the swing supporting legs 15 need to stretch out or swing out to expand the supporting spans during the operations of the crane. The fixed supporting legs serve as guiding and connecting mechanisms of the telescopic supporting legs, and the swing supporting legs have no corresponding fixed supporting legs. The swing supporting legs are connected with the vehicle frame by pin shafts, and the fixed supporting legs can be connected with the vehicle frame by welding or the pin shafts. Referring to FIG. 3a, fixed supporting legs 31 are generally welded on the vehicle frame 32; and referring to FIG. 3b, the fixed supporting legs 31 of some cranes are connected with the vehicle frame 32 by pin shafts 33.
Before the cranes travel on the roads, some supporting legs need to be demounted, and the supporting legs are mounted prior to operations. The to-be-demounted supporting legs herein refer to one kind of the following legs: the telescopic supporting legs, the swing supporting legs and the fixed supporting legs which are detachably connected (wherein one common form is pin shaft connection).
Referring to FIG. 3b, the demounting and mounting methods of the fixed supporting legs connected with the vehicle frame by the pin shafts are described below: the demounting and mounting manners of the fixed supporting legs connected by the pin shafts include a hydraulic manner, a mechanical manner, an electrical manner and a pneumatic manner. In the hydraulic manner, the connected pin shafts 33 are demounted and mounted by a hydraulic cylinder so as to separate and connect the fixed supporting legs 31 and the vehicle frame 32. In the mechanical manner, the connected pin shafts 33 are mainly demounted and mounted manually or via other simple auxiliary tools so as to separate and connect the fixed supporting legs 31 and the vehicle frame 32. The electrical and pneumatic demounting and mounting processes are the same as those of the hydraulic manner. With respect to the demounting and mounting methods of the telescopic supporting legs and the swing supporting legs, reference can be made to the demounting manner of the fixed supporting legs connected by the pin shafts.
The demounting and mounting methods of the fixed supporting legs connected with the vehicle frame by the pin shafts are described below again: the demounting and mounting manners of the fixed supporting legs connected by the pin shafts include the hydraulic manner, the mechanical manner, the electrical manner and the pneumatic manner. In the hydraulic manner, the connected pin shafts 33 are demounted and mounted in the pin shaft holes 33a by the hydraulic cylinder so as to separate and connect the fixed supporting legs 31 and the vehicle frame 32. In the mechanical manner, the connected pin shafts 33 are mainly demounted and mounted manually or via other simple auxiliary tools so as to separate and connect the fixed supporting legs 31 and the vehicle frame 32. The connection manner thereof is as shown in FIG. 3b. The electrical or pneumatic demounting and mounting processes are the same as those of the hydraulic manner.
At present, the supporting legs on the main crane 41 are demounted and mounted by adopting an auxiliary crane 42 in the field of wheeled cranes. The traditional demounting and mounting operation states are shown in FIG. 4.
In the prior art, the specific implementation method and steps of demounting the supporting legs are as follows:
First step, the main crane stops in an area in which it is convenient for the operation of the auxiliary crane, and when the to-be-demounted supporting leg is at a conveniently demounted position. The connecting pipeline, oil cylinder and the like of the supporting leg and the vehicle frame are demounted.
Second step, the auxiliary crane arrives at a proper position, prepares for lifting, adjusts the operation part and lifts the to-be-demounted supporting leg. If the auxiliary crane is an irremovable crane, the auxiliary crane also needs to carry out such operations as adjusting the posture after arriving at the proper position.
Third step, in conjunction with the auxiliary crane, the pin shafts are manually pulled out or the pin shafts are pulled out by the hydraulic cylinder. The auxiliary crane is operated to lift the supporting leg and place the same onto a transport tool.
Fourth step, the posture of the operation part of the auxiliary crane is adjusted, or the operation position of the auxiliary crane is adjusted to demount the remaining supporting legs until the supporting legs are all demounted.
Fifth step, the auxiliary crane resets, and the main crane and a transport vehicle head for the operation site together.
After arriving in the vicinity of the operation site, the supporting legs are mounted in place in sequence; and at this time, the crane can start working. In the prior art, the specific implementation and steps of mounting the supporting legs are as follows:
First step, the main crane stops in an area in which it is convenient for the operation of the auxiliary crane.
Second step, the auxiliary crane arrives at a proper position, prepares for lifting, lifts the supporting leg from the transport tool, selects a proper lifting height and posture, aligns the supporting leg to a pin shaft hole on the vehicle frame and inserts the pin shaft in the mechanical manner or the hydraulic manner. If the auxiliary crane is the irremovable crane, the auxiliary crane also needs to carry out such operations as adjusting the posture after arriving at the proper position.
Third step, the pipeline and the like between the supporting leg and the vehicle frame are connected, and then one swing supporting leg (or a fixed supporting leg connected by the pin shaft) is mounted.
Fourth step, the posture of the operation part of the auxiliary crane is adjusted, or the operation position of the auxiliary crane is adjusted to mount the next supporting leg until the supporting legs are all mounted.
Fifth step, the auxiliary crane resets, and the auxiliary crane and the transport vehicle evade an operation space.
Sixth step, the main crane adjusts the movable supporting leg, locates in a travelling state, arrives at a proper operation position and lifts the supporting leg, and the operation part of the main crane is operated to carry out the lifting operation.
The inventor finds that at least the following problems exist in the prior art:
When the existing wheeled crane is in the travelling state, some supporting legs need to be demounted to be separately transported; and during the operation, the demounted parts are assembled to complete the lifting operation. Usually, the auxiliary crane completes the demounting and mounting operations of the supporting legs of the crane, thus the demounting and mounting operations are troublesome, which not only increases the operation cost, but also wastes time, moreover, the dependency is high, and the operation space requirements are high.